Increased intakes of vitamin
D during pregnancy may reduce the development
of pre-eclampsia by about 25 percent, suggests a study
with over 20,000 Norwegian women.

The risk of pre-eclampsia was 27 per cent lower in
women who consumed vitamin D supplements with daily
doses of 10 to 15 micrograms, compared to women who
did not take supplements, according to researchers
from the Norwegian Institute of Public Health.

However, a correlation between vitamin D intake and
omega-3 fatty acid intake was observed, and the researchers
noted that further research is needed to disentangle
the separate effects of these nutrients.

Pre-eclampsia, affecting two to three per cent of
all pregnancies, occurs when a mother's blood pressure
rises to the hypertensive range, and excretion of
protein in the urine becomes too high. It is estimated
to be responsible for about 60,000 deaths worldwide.

It is not known why some expectant mothers develop
pre-eclampsia, although oxidative stress has been
proposed to play a part. The role of antioxidants
to reduce oxidative stress had been supported by a
small clinical trial that linked vitamin C and E intake
to fewer biomarkers for pre-eclampsia for predominantly
low-risk participants.

However, subsequent studies, including a study published
in The New England Journal of Medicine (Vol. 354,
pp. 1796-1806) and a Cochrane Systematic Review (2007,
Issue 4), found that vitamins C and E had no effects
on the risk of pre-eclampsia.

The new study, published in Epidemiology suggests
that vitamin D supplementation may reduce the risk
of developing the potentially fatal condition.

Led by Helle Margrete Meltzer, the researchers examined
the relationship between vitamin D intakes during
pregnancy and the risk of pre-eclampsia in 23,423
would-be first time mothers participating in the Norwegian
Mother and Child Cohort Study.

The women answered a general health questionnaire
at the fifteenth week of pregnancy and again at the
thirtieth week, while a food frequency questionnaire
was administered at week 22.

According to the Norwegian findings, women with a
daily intake of between 15 and 20 micrograms of vitamin
D from diet and supplements had a 24 per cent lower
risk of developing pre-eclampsia compared to women
who consumed less than 5 micrograms per day.

The overriding benefits were observed for vitamin
D from supplements, with a daily dose of 10 to 15
micrograms linked to a 27 per cent reduction, compared
to women who did not take supplements.

These findings are consistent with other reports
of a protective effect of vitamin D on pre-eclampsia
development, wrote Meltzer and her co-workers.

However, because vitamin D intake is highly
correlated with the intake of long chain omega-3 fatty
acids in the Norwegian diet, further research is needed
to disentangle the separate effects of these nutrients,
they concluded.